Corrosion inhibiting method using substituted succinimides

ABSTRACT

Substituted succinimides and derivatives thereof, formed by (1) reacting a hydrocarbon with a maleic compound or a derivative thereof to yield a hydrocarbon succinate and then (2) reacting the hydrocarbon succinate with an amine to form an imide; and to the uses of these hydrocarbon succinimides, for example in aqueous and/or oxygenated systems, as illustrated by aqueous brines such as in water flooding systems, cooling systems such as in cooling towers, auto radiator systems, etc., drilling muds, air drilling systems, etc., as corrosion and/or scale inhibitors, etc.

United States Patent 1 1 Oude Alink CORROSION INHIBITING METHOD USING SUBSTITUTED SUCCINIMIDES [75] Inventor: Bernardus A. Oude Alink, St. Louis,

[73] Assignee: Petrolite Corporation, Wilmington,

Del.

[22] Filed: Feb. 16,1971

[21] Appl. No.: 115,818

[52] US. Cl. 21/2.7 R, 252/8.55 E, 252/392, 252/148 [51] Int. Cl. C23K 11/04, C23g H06 [58] Field of Search 2l/2.7; 252/392, 252/8.55 E, 148

[56] References Cited UNITED STATES PATENTS 2,466,530 4/1949 Blair et al. 252/392 2,568,876 9/1951 White et a1. 252/392 X 2,604,451 7/1952 Rocchini 252/392 X 2,793,997 5/1957 Hughes 21/2.7 X 2,822,330 2/1958 Riggs et a1. 252/392 X 2,974,023 3/1961 Cyba et al 252/392 X 3,003,961 10/1961 Andress et al. 252/392 X Oct. 2, 1973 3,004,987 10/1961 Paris et al. 252/392 X 3,024,237 3/1962 Drummond et a1 252/392 X 3,135,765 6/1964 Andress et al. 252/392 X 3,184,474 5/1965 Catto et al 252/392 X 3,200,106 8/1965 Dickson et al.. 252/392 X 3,224,968 12/1965 Hinkamp 252/392 X 3,287,271 11/1966 Stuart et a1. 252/392 X 3,347,645 10/1967 Pietsch et al. 252/392 X 3,458,444 Shepherd et a1 252/392 X Primary ExaminerBarry S. Richman Att0rney-Sidney B. Ring [57] ABSTRACT Substituted succinimides and derivatives thereof, formed by (l) reacting a hydrocarbon with a maleic compound or a derivative thereof to yield a hydrocarbon succinate and then (2) reacting the hydrocarbon succinate with an amine to form an imide; and to the uses of these hydrocarbon succinimides, for example in aqueous and/or oxygenated systems, as illustrated by aqueous brines such as in water flooding systems, cooling systems such as in cooling towers, auto radiator systems, etc., drilling muds, air drilling systems, etc., as corrosion and/or scale inhibitors, etc.

3 Claims, No Drawings I have now discovered that a certain class of com- 7 pounds are very effective in aqueous and/or oxygenated systems. These compounds may be characterized as hydrocarbon succinimides and derivatives thereof,

formed by (1) reacting a hydrocarbon with a maleic I compound or a derivative thereof to yield a hydrocarbon succinate and then (2) reacting the hydrocarbon succinate with an amine to form an imide.

The hydrocarbon succinates are illustrated by the following idealized formulae where R is a hydrocarbon moiety, preferably alkyl or alkenyl:

where n is, for example 1 5, or even 25 or more in certain instances.

The hydrocarbon succinates may also be a mixture of one or more of the above formulae.

Stated another way, the hydrocarbon moiety may have one or more maleic units attached thereto; said maleic units may be attached at one or more positions on the hydrocarbon moiety, may be attached directly to the hydrocarbon moiety or to one or more other maleic molecules, etc.

The term hydrocarbon succinate relates to the product formed by the action of a hydrocarbon with a maleic anhydride, or an equivalent or a derivative thereof. It also includes derivatives of hydrocarbon succinates.

The term"maleic compound relates to maleic anhydride, maleic acid, maleic type anhydrides or acids, esters and other derivatives thereof.

Any suitable hydrocarbon can be employed in preand may be straight chain or branched. lt may also have other groups such as cycloaliphatic, aryl, etc., groups attached to the chain.

ln the preferred embodiment the hydrocarbons are 5 alkyl or alkenyl and because of the economics involved are generally of petroleum origin.

Because of its commercial importance, maleic anhydride is employed to illustrate this invention. Examples of other acids or anhydrides which may be reacted include citraconic acid, ethyl-maleic acid, glutaconic acid, itaconic acid, methylitaconic acid, etc. The term hydrocarbon succinates" and maleic compound" includes these acids, esters and other derivatives. One preferred class of compounds employed herein are alkenyl succinimides. These may be defined by the following general formulae.

where R is an alkenyl group and N is the moiety ofari amino group comprising the imide structure and Y is .the bridge between amino groups, hereinafter defined more fully. Preferably R is an alkenyl group containing from about 5 to 100 carbon atoms, atoms, such as from about 15 to 80 carbons, for example from about 15 to 70 carbons but preferably from about to 70 carbons.

In one class of compounds, R is a polyolefin, that is, the alkenyl radical, is derived from an olefin containing from two to five carbon atoms. Thus, the alkenyl radical is obtained by polymerizing an olefin containing from two to five carbon atoms to form a hydrocarbon. Such olefins are exemplified by ethylene, propylene, l-butene, 2-butene, isobutene, and mixtures thereof. Since the methods of polymerizing the olefins to form polymers thereof is immaterial in the formation of the compounds described herein, any of the numerous processes available can be used therefor.

The reaction between a polyolefin and maleic anhydride is an uncatalyzed addition reaction which should not be confused with a copolymerization reaction such as that obtained with a vinyl monomer and maleic anhydride. This reaction can proceed in a mol ratio of the polyolefin to the maleic anhydride of 1:1 to 1:10, preferably from 1:1 to 1:5. The reaction temperature can vary from 150 240C. Because of the greater yield of products obtained thereby, it is preferred to use the high range of temperatures (e.g., 190 240C). The preparation of the alkenyl succinic anhydride is illustrated by the following reaction in which polyisobutene and maleic anhydride are employed.

ITO-(l3 CH; IOI

which when reacted with an amine yields the following product I can also prepare the hydrocarbon succinates by reacting a hydrocarbon with maleic anhydride under free radical forming conditions. In one embodiment, the hydrocarbon, maleic anhydride and a peroxide are reacted at a temperature sufficiently high to promote free radical formation. Since heat promotes free radical formation, a temperature sufficiently high to promote the decomposition of the peroxide, without causing decomposition of reactants and products, is employed. Depending on the peroxide, temperatures of about 100 250C., such as about 125 to 225, for example about 150 to 215, but preferably about l70 to 200", are employed. The temperature should be sufficiently high to keep all reactants in solution or in a molten state.

In th case of di-tert-butyl peroxide the best yields are obtained in the ranges of about 100 to 250C, but preferably about 170 to 200C.

Reaction times will depend on various factors such as for example on the particular reactants, reaction conditions, etc. A reaction time sufficient to effect the desired degree of reaction completion is employed. Ordinarily, reaction times of from about 0.5 to 6 hours, such as about 1 to hours, for example about L5 to 4.5 hours, but preferably about 2 to 4 hours are employed. Shorter or longer times may be employed to push the reaction to the desired degree of completion depending on various factors, such as reactants, conditions, peroxides, etc.

Any suitable free-radical producing agent capable of forming reactive sites can be employed. These include peroxides, hydroperoxides, etc., for example benzoyl peroxide, acetyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxide, tert-butyl hydroperoxide, methyl benzyl hydroperoxide, cumene hydroperoxidc, peracetic acid, tert-butylpermaleic acid, lauryl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, di-tert-buty] diperphthalate, tert-butyl peracetate, and the like.

Other sources of free radicals besides peroxides can also be employed, for example high energy ionizing irradiation, etc., cobalt in conjunction with hydroperoxides, inorganic peroxy compounds such as persulfates, hydrogen peroxide, etc., azo compounds of the general formula R-N=N-R such as azobenzene, azomethane, azobisisobutyronitrile, etc., acyl-aryl nitrosoamides such as nitrosoamides such as nitrosoanilide, etc.

The polyamines employed to form the imide include those of the following formula:

where n is for example 1 or greater, where A is a divalent radical, for example straight or branched and m is for example 2 H) or greater. These include the following:

NH CHgCHgN 3II H, etc,

Other examples include the following alkylated polyamines for example of the formula cloalkyl, alkyl, alkenyl, alkynyl, aryl, etc. The preferable type is of the formula If H RN(AI\I),,H (R is straight chain or branch) Examples include the following:

l CuHaaN-CaHuN-C2H4NH Other suitable amines are exemplified by:

cm -"o omen, 611mm (Jil -O H C I Q Aromatic polyamines can also be employed, for ex ample:

such as where A is t 1. (CH such as where x is 1 or greater,

- 3. cycloaliphatic, etc.

Typical examples include alkanol amines, ethanol amine, propanol amine, butanol amine, decanol amine, etc.

, substituted derivatives thereof, etc,

NHZ:

Examples of other amines include the following cyclic amines such as where A is alkylene and R is a hydrocarbon or hydro gen,

where R is hydrocarbon; or heterocyclic amines such as imidazolenes, for example H1NCH,CH,N I i etc.

anhydride mol ratio is about 0.8 to 1 to l to l.

The substituted succinimides can be prepared by heating a mixture of the substituted succinic anhydrides and the amines at temperatures of 150 200C. A vacuum may be applied to removethe water produced in the reaction. An alternative route is to reflux a mixture of the substituted succinic anhydride and the amine in a solvent such as benzene, toluene or xylene and to remove the water produced azeotropically.

The following examples are presented by way of illustration and not of limitation.

EXAMPLE 1 A sample of 420 grams of polyisobutene having a molecular weight of 498 and 98 grams of maleic anhydride were introduced in a reaction vessel and heated under continuous stirring at a temperature of 197 214C. for 21 hours. The resulting polyisobutene-substituted succinic anhydride shows an acid number of 106.25 mg. NaOH/g and a molecular weight of 552.

EXAMPLE 2 To a sample of 16.4 grams of the polyisobutenesubstituted succinic anhydride prepared as in Example 1 was added 150 cc of isopropanol. Into the mixture was passed ammonia gas for 3 hours. From the resulting reaction mixture the solvent was removed and the product was heated under a vacuum at C. for 9% hour.

EXAMPLE 3 A mixture of 51.8 grams of the polyisobutenesubstituted succinic anhydride prepared as in Example 1, 6.1 grams of monoethanolamine and 200 cc of toluene was refluxed under azeotropical conditions for 9 hours, after which time the theoretical amount of water was produced. The solvent was removed under diminished pressure to yield 56.2 grams of product.

EXAMPLE 4 In a manner like that described in Example 3, 10 grams of polyisobutene-substituted succinic anhydride and 2.00 grams of diglycolamine were refluxed under azeotropical conditions using toluene (150 cc) as the solvent. Isolated was 12.0 grams of product.

EXAMPLE 5 In a manner like that described in Example 3, 21.3 grams of p0lyisobutene-substituted succinic anhydride and 5.35 grams of N-(-2-aminoethyl) morpholine in 200 cc of toluene were refluxed under azeotropical conditions for 9 hours to yield 26 grams of product.

EXAMPLE 6 In a manner like that described in Example 3, 23.0 grams of polyisobutene-substituted succinic anhydride and 4.6 grams of 2-(2-aminoethylamino)ethanol in 100 cc of toluene were refluxed under azeotropical conditions for hours to yield 27 grams of product.

EXAMPLE 7 In a manner like that described in Example 3, 52.8 grams of polyisobutene-substituted succinic anhydride and 13.2 grams of l-aminoethyl piperazine in 95 cc of tolene were refluxed for 9 hours under azeotropical conditions to yield 64.5 grams of product.

EXAMPLE 8 In a manner like that described in Example 3, 310.8 grams of polyisobutene-substituted succinic anhydride and 61.8 grams ofdiethylene triamine in 372.2 grams of xylene were refluxed for 9 hours after which time 19.8 grams of water was formed. There was isolated 353 grams of product.

EXAMPLE 9 EXAMPLE 10 A mixture of 68.8 grams of polyisobutene-substituted succinic anhydride, prepared as in Example 1, and 8.2 grams of Amine No. 1, a mixture of 68 percent diethylene triamine, 30 percent of triethylene, and 2 percent of tetraethylene pentamine, was heated slowly under a vacuum to 195 C. and kept at this temperature for 3 hours. The reaction product was cooled to room temperature and 73 grams of product was isolated.

EXAMPLE 11 In a manner like that described in Example 3, 51.8 grams of p0lyisobutene-substituted succinic anhydride and 14.1 grams of dipropylene triamine in 66 grams of toluene were refluxed under azeotropical conditions for 6 hours to yield 64 grams of product.

EXAMPLE 12 A sample of grams of polyisobutene having a molecular weight of 320 and 24.5 grams of maleic anhydride were reacted at 200 C. for 17 hours to yield a polyisobutene-substituted succinic anhydride.

EXAMPLE 13 In a manner like that described in Example 2, 14 grams of polyisobutene-substituted succinic anhydride prepared as in Example 12, was reacted with ammonia in isopropanol as the solvent to yield 14 grams of product.

EXAMPLE 14 In a manner like that described in Example 3, 16.7 grams of polyisobutene-substituted succinic anhydride, prepared as in Example 12, was reacted with 2.45 grams of monoethanolamine to yield 17.8 grams of product.

EXAMPLE 15 A sample of 1 14 grams of polyisobutene having a molecular weight of 460 and 24 grams of maleic anhydride were heated at 200C. for 17 hours and for 5 hours at 220C. to yield a polyisobutene-substituted succinic anhydride.

EXAMPLE 16 In a manner like that described in Example 2, 14.5 grams of polyisobutene-substituted succinic anhydride prepared as in Example 15, was reacted with ammonia in isopropanol as the solvent to yield 14.5 grams of product.

EXAMPLE 17 In a manner like that described in Example 3, 22.1 grams of polyisobutene-substituted succinic anhydride prepared as in Example 15, was reacted with 2.5 grams of monoethanolamine to yield 24 grams of product.

EXAMPLE 18 A sample of polyisobutene having a molecular weight of 750 was reacted with 24 grams of maleic anhydride at 210C. for 24 hours to yield a polyisobutenesubstituted succinic anhydride.

EXAMPLE 19 In a manner like that described in Example 3, 37.9 grams of polyisobutene-substituted succinic anhydride prepared as in Example 18 was reacted with 2.72 grams of monoethanolamine to yield 39.5 grams of product.

EXAMPLE 20 A sample of 12.5 grams of tetradecene-substituted succinic anhydride and 2.6 grams of monoethanolamine were reacted in a manner like that described in Example 3 to yield 14.5 grams of product.

EXAMPLE 21 A sample of 32.2 grams of hexadecene-substituted succinic anhydride and 6.1 grams of monoethanolamine were reacted in a manner like that described in Example 3 to yield 36.5 grams of product.

EXAMPLE 22 A sample of 16.0 grams of a substituted succinic anhydride derived from the reaction of a fraction of C C alpha-olefins and maleic anhydride and 2.2 grams of monoethanolamine were reacted in a manner like that described in Example 3 to yield 18 grams of product.

EXAMPLE 23 A succinic amide was prepared according to a procedure disclosed in US. Pat. No. 3,251,776, Example 1, from hydroxyethyl ethylene diamine and succinic anhydride, by adding 104 grams (1 mole) of hydroxyethyl ethylene diamine gradually to a mixture of 100 grams of succinic anhydride and 204 grams of water.

The hydrocarbon can also be reacted with maleic under free radical conditions.

In one embodiment maleic anhydride and the peroxide, preferably as a solution, are added to molten wellstirred hydrocarbon and the reaction allowed to react to completion. The product is precipitated by pouring into a liquid in which the desired product is insoluble, and the by-products are soluble, such as methanol, and the wax separated therefrom by any suitable means such as by filtration, etc. Thereafter the product is washed with methanol and collected by filtration.

In another embodiment, the hydrocarbon-maleic half-ester is converted to the anhydride in situ.

The following examples are presented by way of illustration and not of limitation.

EXAMPLE I A Fourty-four pounds of molten hydrocarbon, m.w. 675,*( *the hydrocarbon is a petrolatum), (29.5 moles) are charged to the reactor and heated to 205C. A mixture of 17.6 pounds of isopropyl maleate (50.5 moles) and 2.2 pounds of di-t-butyl peroxide were added over a six hour period with the temperature maintained at 205 216C. Then the solution is stirred one-half hour at 215C. Unreacted maleic anhydride was removed under vacuum. The solution was cooled to l C. and 21 pounds of aromatic solvent were added. Sixty-nine and one-half pounds of product were obtained.

EXAMPLE 1 B To a clean reactor were charged six and one-eighth pounds of tetraethylene pentamine (l4.7 moles) and 18% pounds of aromatic solvent. This was heated to 90 95C. and 24.4 pounds of the product of Ex. 1 A were added slowly. Seven and three-fourths pounds of aromatic solvent were added. Solution was heated to 135C., and then 0.8 pounds H O were removed at 140 165C. Twenty-one and one-fourth pounds of aromatic solvent were added to complete the final product.

This solution, approximately 50 percent active, is employed as a corrosion inhibitor.

In summary, the hydrocarbon which is reacted with maleic anhydride may be an alkane or an alkene. The alkene may be straight chain or branched. They include alkene polyolefins, such as the polyisobutenes, etc., as well as linear alkenes, for example the formula R CH CH where R is a linear hydrocarbon having, for example, 3 or more carbons such as pentene, hexene, heptene, octene, decene, undecene, dodecene, tridecene, tetradecene, hexadecene, heptadecene, octadecene, etc., having up to about 100 or more carbons, but preferably up to about 70 carbons.

The term amine as employed herein also includes ammonia.

USE IN BRINES This phase of the invention relates to the prevention of corrosion in systems containing a corrosive aqueous medium, and most particularly in systems containing brines.

More particularly, this invention relates to the prevention of corrosion in the secondary recovery of petroleum by water flooding and in the disposal of waste water and brine from oil and gas wells. Still more particularly, this invention relates to a process of preventing corrosion in water flooding and in the disposal of waste water and brine from oil and gas wells which is characterized by injecting into an underground formation an aqueous solution containing minor amounts of compositions of this invention, in sufficient amounts to prevent the corrosion of metals employed in such operation. This invention also relates to corrosion inhibited brine solutions of these compounds.

When an oil well ceases to flow by the natural pressure in the formation and/or substantial quantities of oil can no longer be obtained by the usual pumping methods, various processes are sometimes used for the treatment of the oil-bearing formation in order to increase the flow of the oil. These processes are usually described as secondary recovery processes. One such process which is used quite frequently is the water flooding process wherein water is pumped under pressure into what is called an injection well and oil, along with quantities of water, that have been displaced from the formation, are pumped out of an adjacent well usually referred to as a producing well." The oil which is pumped from the producing well is then separated from the water that has been pumped from the producing well and the water is pumped to a storage reservoir from which it can again be pumped into the injection well. Supplementary water from other sources may also be used in conjunction with the produced water. When the storage reservoir is open to the atmosphere and the oil is subject to aeration this type of water flooding system is referred to herein as an. open water flooding system. If the water is recirculated in a closed system without substantial aeration, the secondary recovery method is referred to herein as a closed water flooding system.

Because of the corrosive nature of oil field brines, to economically produce oil by water flooding, it is necessary to prevent or reduce corrosion since corrosion increases the cost thereof by making it necessary to repair and replace such equipment at frequent intervals.

I have now discovered a method of preventing corrosion in systems containing a corrosive aqueous media, and most particularly in systems containing brines, which is characterized by employing the compositions of this invention.

I have also discovered an improved process of protecting from corrosion metallic equipment employed in secondary oil recovery by water flooding such as injection wells, transmission lines, filters, meters, storage tanks, and other metallic implements employed therein and particularly those containing iron, steel, and ferrous alloys, such process being characterized by employing in water flood operation the compositions of this invention.

This phase of the invention then is particularly concerned with preventing corrosion in a water flooding process characterized by the flooding medium containing an aqueous or an oil field brine solution of these compounds.

In many oil fields large volumes of water are produced and must be disposed of where water flooding operations are not in use or where water flooding operations cannot handle the amount of produced water. Most States have laws restricting pollution of streams and land with produced waters, and oil producers must then find some method of disposing of the waste produced salt water. In many instances, therefore, the salt water is disposed of by injecting the water into permeable low pressure strata below the fresh water level. The formation into which the water is injected is not the oil producing formation and this type of disposal is defined as salt water disposal or waste water disposal. The problems of corrosion of equipment are analogous to those encountered in the secondary recovery operation by water flooding.

The compositions of this invention can also be used in such water disposal well thus providing a simple and economical method of solving the corrosion problems encountered in disposing of unwanted water.

Water flood and waste disposal operations are too well known to require further elaboration. In essence, in the present process, the flooding operation is effected in the conventional manner except that the flooding medium contains a minor amount of the compositions of this inventor, sufficient to prevent corrosion, in concentrations of about ppm to 10,000 ppm, or more, for example, about 50 to 5000 ppm, but preferably about to 1,500 ppm. The upper limiting amount of the compounds is determined by economic considerations. Since the success of a water flooding operation manifestly depends upon its total cost being less than the value of the additional oil recovered from the oil reservoir, it is quite important to use as little as possible of these compounds consistent with optimum corrosion inhibition. Since these compounds are themselves inexpensive and are used in low concentrations, they enhance the success ofa flood operation by lowering the cost thereof.

In addition, these compounds are not sensitive to oxygen content of the water and these are effective corrosion inhibitors in both open water flooding systems and closed water flooding systems.

While the flooding medium employed in accordance with the present invention contains water or oil field brine and the compounds, the medium may also contain other materials. For example, the flooding medium may also contain other agents such as surface active agents or detergents which aid in wetting throughout the system and also promote the desorption of residual oil from the formation, sequestering agents which prevent the deposition of calcium and/or magnesium compounds in the interstices of the formation, bactericides which prevent the formation from becoming plugged through bacterial growth, tracers, etc. Similarly, they may be employed in conjunction with any of the operating techniques commonly employed in water flooding and water disposal processes, for example five spot flooding, peripheral flooding, etc., and in conjunction with other secondary recovery methods.

Corrosion tests were made using sand blasted I020 mild steel coupons monitored by a polarization resistance meter, a PAIR instrument described in U.S. Pat. No. 3,406,101. These tests were made in cylindrical containers of 1500 cc volume with provision for constant stirring by means of a motor driven impeller. A thermostatically controlled immersion hcatcr maintained an average temperature of C. and an air inlet kept the fluids constantly saturated with air. Between each test the cylinder was cleaned with steam, benzene, acetone and thoroughly washed with clean water. Results of these corrosion tests made in various aqueous environments are shown in the following Table.

Protection is calculated in the usual manner from corrosion rate (R,) of fluids without inhibitor and corrosion rate (R in presence of particular inhibitor according to the formula (R, RQ/R X 100 Percent protection.

TABLE A Corrosion results in Laboratory brine (4.2% NaCl, 1.7% Mg Cl 0.15 CaCI 0.09% Na SO, pH 6.0)

Test Data. Continuous Aerated Brine. Temperature 78 C.

Cor mpy Pro- Concentration rosion after tection Inhibitor of Inhibitor Rates 24 hr. after ppm 1 hr. 24 hr.

None 0 88 0 Example l 1000 39 76 l2.5 Example 2 500 16.5 16.1 96.4 Example 3 500 L3 0.l5 99.8 Example 4 500 19.5 4.1 95.3 Example 5 500 0.15 0.05 99.9 Example 6 500 42 ll 87.3 Example 7 500 27 7.0 92.0 Example 8 500 6.8 3.7 958 Example 9 500 54 4.3 95.] Example 10 500 27 2.6 97.0 Example ll 500 I3 6.6 92.5 Example l3 l000 0.5 0.2 99.8 Example 14 I000 4 0.4 99.5 Example 16 1000 0.4 1.3 98.5 Example 17 1000 2.5 0.3 99.7 Example [9 500 3.4 0.8 99.l Example 20 500 47 10 88.7 Example 2l 500 33 18.5 78.9 Example 22 l000 0.7 0.08 99.9 Example 23 I000 77 8l 8.0

Note: Ex. I and Ex. 23 are not hydrocarbon substituted imides.

USE IN FLUIDS FOR DRILLING WELLS This phase of the invention relates to the use of the compounds of this invention as corrosion inhibitors in producing an improved drilling fluid useful in drilling oil and gas wells.

Fluids commonly used for the drilling of oil and gas wells are of two general types; water-base drilling fluids comprising, for example, a clay suspended in water, and oil-base drilling fluids comprising, for example, a clay or calcium carbonate suspended in mineral oil.

A third type of drilling fluid which has recently been developed, is one of oil-in-water or water-inoil emulsion, for example, emulsions of mineral oil in water or water in mineral oil formed by means of emulsifiers such as sulfuric acid; Turkey-red oil; soaps of fatty acids, for example, sodium oleate; emulsoid colloids, for example starch, sodium alginate, etc. Varying amounts of finely divided clay, silica, calcium carbonate, blown asphalt and other materials may be added to these emulsions to improve their properties and control their weight.

I have now discovered that the compositions of this invention can be employed as a corrosion inhibitor in drilling fluids.

USE IN AIR DRILLING It has long been conventional practice in drilling deep bore holes to circulate a drilling mud down through the drill stem and up through the bore hole between the wall of the bore hole and the drill stem for the removal of chips or cuttings from the bore hole. More recently, in the drilling of holes in which wall-support provided by drilling mud is not employed, drilling has been carried out with the use of air for chip removal. Such drilling is not only normally faster than mud drilling, but is indispensable in areas where the supply of water is limited or when drilling through cavernous formations into which the drilling mud flows and becomes lost.

I The increasing popularity of air or gas drilling has come about not only because this method of drilling is frequently faster, as noted above, but for the additional reasons that the drill bits last longer, the provision and handling of water under wide ranges of temperature conditions is avoided, boring samples are easily observed when they are not mixed with mud, and there is no loss involved as in the case of mud drilling when drilling through cavernous formations. Furthermore, prompt removal of water entering the hole maintains a dry hole and the likelihood of wall collapse is thereby reduced.

In a typical air drilling operation there may be provided, for example, an up-flow of air in the bore hole having a velocity of the order of 3,000 feet per minute. This flow of air upwardly throughthe bore hole, which is produced by air pumped downwardly through the drill stem, provides adequate removal of cuttings. The air is delivered to the drill stem at pressures of to 60 lbs. per square inch and for dewatering or for breaking obstructions, as will be hereinafter described, the pressures may be increased to 180 to 200 lbs. or more per square inch.

Air drilling operations are frequently hampered by the inflow of water into the bore hole when the drill bit is penetrating a water bearing stratum or when the bore hole has passed through a water bearing stratum that has not been cased. Normally, if drilling proceeds uninterruptedly both before and during penetration into a water bearing stratum, the flow of air is sufficient to blow the water out of the bore hole along with the cuttings and drilling dirt. There are, however, two major problems encountered in air drilling when water is entering the bore hole. The first problem occurs when there is a small inflow of water sufficient to cause a dampening of the cuttings which, under certain conditions, will then ball-up, clogging and sometimes jamming the drill bit. The second problem is encountered when there is a substantial amount of water remaining in the bottom of the bore hole during drilling causing a sloughing of the side wall of the bore hole. This latter condition may arise even though the water entering the bore hole is being blown out of the hole as fast as it enters. If there is a substantial flow of water past a region of the bore hole susceptible to this condition, the water passing that region of the bore hole may cause a sloughing of the side wall.

The addition of foam forming materials to the air flow when air drilling is employed in conjunction with sufficient water to provide foaming gives rise to numerous advantages in drilling operations. The water may be introduced either through a water bearing stratum being penetrated by the drill bit, or alternatively, if the hole is dry, water may be introduced from the surface of the earth through the drill stemin conjunction with the delivery of compressed air and foam forming material through the drill stem to the drill bit. In either case the water may be said to be existing in the bore hole, and drilling operations are described in US. Pat. No. 3,130,798.

The compositions of this invention can be employed as a corrosion inhibitor in a drilling system.

USE IN ANTlFREEZE SYSTEMS The compositions of this invention are useful in antifreeze formulations, such as for use as corrosion inhibitors in cooling systems such as aqueous glycol antifreeze such as in automobiles, trucks, aircraft, etc.

USE AS SCALE INHIBITORS This invention also relates to the use of the compositions of this invention in inhibiting the formation of scale on surfaces, such as on pipes or other equipment. They are particularly useful in inhibiting the deposit of scale in equipment used in producing and handling crude oil since water produced from the earth, along with oil, also deposits inorganic solids such as scale in the well tubing or more commonly in traps, heaters or other surface equipment and even in pipelines. They are also valuable in inhibiting scaling which may accumulate in steam generating equipment if hard waters are used. Utility is not limited to such characteristic ap plications but can be used in other instances where scale or deposits of inorganic solids from aqueous media constitute a nuisance in industrial or other activities.

The process is particularly effective in preventing and/or reducing the formation of scale by introducing the composition of this invention with the incoming waters before scale has accumulated, as a preventative measure. It is usually preferred to introduce by means of a proportioning pump a continuous stream of the compositions into the incoming scale-forming water.

The composition of the invention are especially effective in minor amounts in the inhibition of scaling on metal surfaces by calcium sulfate, barium sulfate, and calcium carbonate. They are useful in the oil production industry to prevent deposits of these scaleproducing compounds on metal surfaces of pumps, pipes, valves, tanks, and the like when waters containing the scale-producing compounds (or precursors thereof, e.g., calcium bicarbonate) are treated in the concentrations of about 0.5 to 5,000 or more parts per million, such asfrom about 5 to 1,000 ppm, but preferably about 10 to 500 ppm. The optimum phase will vary with the particular compound, system, etc. Higher concentrations can also be employed such as 10,000 or more ppm. The optimum ppm is a balance between function and cost. Places where scale buildup is most likely to become troublesome are those in the liquid handling systems wherein there is a change in fluid pressure, a change in fluid temperature, or a change in The invention may be used in waterflood systems used to inject water into subterranean formations, wherein the water is brackish or is a brine conducive to scale formation on metal surfaces of the waterflood system. Typical brines encountered in waterflood operations, wherein water is drawn from sources available at or near the water-flood site, are in mg/liter:

Brine A Brine B 15 Total Hardness (CaCO;,) mg/l 5,300 3,400 Calcium (CaCO mg./l 4 900 1.600 Sulfate (NaSO mg/l 4,750 pH 7.8 8.3

The compositions of the invention are useful in a number of areas where scaling of metal surfaces, particularly ferrous metal surfaces, by barium sulfate, calcium sulfate and/or calcium carbonate is a problem. By control of scale formation, breakdowns, maintenance, cleaning and repairs caused or necessitated by scale formations can be minimized. For example, these compositions are effective in preventing barium sulfate scale in waterflood systems. In oil producing wells which produce oil and brine, bad scaling by barium sulfate or calcium carbonate can cause the wells to be pulled every two or three weeks. By batch treatment or continuous treatment thereof with these compositions, the well will rarely need to be pulled for reasons of scaling.

These compositions being liquid are easily applied for example by continuous injection from a proportioning pump in contrast to inorganic scale inhibitors.

The effectiveness of the compositions of this invention as scale inhibitors was demonstrated by a test apparatus designed to measure deposition of scale from scaling waters. The apparatus and its operation is described in Oil and Gas Journal, Vol. 67, p. 166 (1969). In this test deposition of calcium sulfate from scaling water was measured.

These scale inhibitor tests were run in conjunction with corrosion tests using the apparatus described for the corrosion tests, namely a cylindrical container of 1500 ml capacity with provision for heating and stirring and in which were placed three sand blasted 1020 mild steel coupons attached to the lid. These tests were conducted at 180F. The effectivenss of the scale inhibitors were determined by a visual examination of the amount of scale (CaSO -CaCO deposited on the metal coupons in 24 hours at l80 F.

The compositions of this invention are effective as scale inhibitors.

USE IN COOLING TOWER OPERATIONS The cost of cooling tower maintenance is often high unless the water is treated to inhibit corrosion, scale deposits, etc.

Certain salts, such as calcium bicarbonate, which are normally present in raw water, tend to break down to form relatively insoluble calcium carbonate which deposits as scale on the surfaces of the circulating water system, thus reducing heat transfer.

In addition, because corrosive materials are present in raw water, corrosion control is also necessary.

The compositions of this invention are particularly effective in inhibiting both scale and corrosion due to a cooling tower water. For example, the compositions of this invention are particularly effective depending on the particular system, etc., at low concentrations, such as from about 0.5 1,000 ppm, for example from about 5 to 500 ppm, but preferably from about to 50 ppm.

The compositions of this invention may also be added to other aqueous and/or oxygenated systems such as steam generating systems, water circulating systems, in diesel locomotive engines, in boiler water, sea-water ship ballast, etc.

The amount of the compositions of the invention to be employed as a corrosion inhibitor can vary widely depending upon particular compounds, the particular system, the amounts of oxygen present, etc. I may employ concentrations of from about 0.5 to l0,000 ppm, such as from about 5 to 7,500 ppm, for example from about 20 to 2,000 ppm, but preferably from about I00 to 1,000 ppm. The optimum amount, to be determined in each instance, which will depend on function and economics, can be lesser or greater than the above amounts under proper conditions.

As is quite evident, new substituted succinimides will be constantly developed which could be useful in our invention. It is, therefore, not only impossible to attempt a comprehensive catalogue of such compositions, but to attempt to describe the invention in its broader aspect in terms of specific chemical names used would be too voluminous and unnecessary since one skilled in the art could be following the description of the invention herein select a useful compound. This invention lies in the use of suitable substituted succinimides and mixtures thereof where appropriate as corrosion inhibitors and/or scale inhibitors in aqueous and/or oxygenated systems and their individual compositions are important only in the sense that their properties can affect this function. To precisely define each specific useful composition and aqueous system in light of the present disclosure would merely call for knowledge within the skill of the art in a manner analogous to a mechanical engineer who prescribes in the construction of a machine the proper materials and the proper dimensions thereof. From the description in this specification and with the knowledge of a chemist, one will know or deduce with confidence the applicability of specific compositions suitable for this invention by applying them in the process set forth herein. In analogy to the case ofa machine, wherein the use of certain materials of construction or dimensions of part would lead to no practical useful result, various materials will be rejected as inapplicable where others would be operative. I can obviously assume that no one will wish to use a useless composition nor will be misled because it is possible to misapply the teachings of the present disclosure to do so. Thus, any substituted succinimide or mixtures containing them that can perform the functions stated herein can be employed,

I claim:

l. A process of inhibiting corrosion of metals and alloys in acidic aqueous media or acidic oxygenated aqueous media which comprises adding to said media a corrosion inhibiting amount of an imide of a hydrocarbon-substituted maleic compound wherein said imide is derived from an alkanolamine.

2. The process of claim I where the hydrocarbon group has l5 to carbon atoms.

3. A process of inhibiting corrosion of metals and alloys in acidic aqueous media or acidic oxygenated aqueous media which comprises adding to said media a corrosion inhibiting amount of an imide of a hydrocarbon'substituted maleic compound wherein said hydrocarbon group is derived from polyisobutene. 

2. The process of claim 1 where the hydrocarbon group has 15 to 70 carbon atoms.
 3. A process of inhibiting corrosion of metals and alloys in acidic aqueous media or acidic oxygenated aqueous media which comprises adding to said media a corrosion inhibiting amount of an imide of a hydrocarbon-substituted maleic compound wherein said hydrocarbon group is derived from polyisobutene. 